The instant application should be granted the priority date of Feb. 19, 2008, the filing date of the corresponding International patent application PCT/EP2008/001263.
The invention relates to a method for controlling longwall operations, having a face conveyor, at least one extraction machine, and a hydraulic shield support, in underground coal mining.
One problem in the automation of longwall controllers is, inter alia, the control of the top canopy-coal face distance, which is referred to hereafter in short as “CaCo”. In general, efforts are made in underground operations of coal mining, after exposure of an overlying strata surface, to support this overlying strata surface as early as possible by appropriate supports, in order to reduce the danger, which exists for reasons of the rock mechanics, of an outbreak of the overlying strata in the area not supported by supports. Because of the operating sequence during the extraction, overlying strata areas without a support foundation necessarily occur in longwall operations. Thus, for example in the case of cutting extraction using a disc shearer loader, the shield support must initially maintain a distance from the coal face at the coal-face-side end of its top canopy so that it is possible for the disc shearer loader to travel past without colliding with the support. If the front disc of the disc shearer loader in the march direction, which typically leads, has cut into the upper stratum of the seam and exposed the overlying strata, it is only possible to advance the shield support at a certain distance behind the disc shearer loader traveling ahead, so that in this area the overlying strata is not supported by the shield support. The distance between the coal-face-side end of the top canopy of the shield support frame and the coal face (CaCo) which thus results depending on the operating state in the longwall operation, i.e., the freely protruding span width of the overlying strata between the coal face and its bearing on the shield support, decisively influences the danger of breakouts in the overlying strata. Any breakout can result in an impairment of the extraction operation, in particular in the case of the desired automation of extraction and support work.
The invention is therefore based on the object of disclosing a method of the type cited at the beginning, using which the top canopy-coal face distance (CaCo) is monitored during advance of the longwall front with respect to a minimization of the breakout danger and is settable.